Method and means for cooling cylinders, etc.



lTED STATES PATENT OFFICE.

VILLI HARPER, JR., OF NEW YORK, N. Y., ASSIGNOB, BY MESNE ASSIGNMENT& TO

SKYWEG AIRCRAFT CORPOMTION', OF NEW YOIRIL N..Y., A COBPORATION O NEW YRK.

METEOD AND HEARS FOR COOLING CYLINDERS, ETC.

Specification of Letters Patent.

Patented J an. 24, 1922.

V To all whom it may camera i by a fluid system wherein the circulation be tween heat absorbing and heat radiating portions of the system is produced by convection, each cylinder constituting an independent unit, and enabling a considerably higher working temperature to be' employed then is now common. The invention will be described with particular reference to its application to rotary cylinder combustion engines, such as the Gnome type wherein the invention is particularly advantageous because it permits a higher workin temperature with consequently increased ei: ficiency, and also because the centri fu al force due to the rapi-d revolution of t e cylinder is evailed of to accelerate the circulation. These engines are widely used at, present in aviation, and it is desirable not only to increase the working temperature in order to increase the efiiciency, but also to provide more uniform cooling than is now obtained with the common form oi air cooling fine carried by the cylinders. EX- perience has shown that the leading side of a roteting cylinder having cooling fins is cooler :than the opposite'side and hence the cylinder in operation gets out dr round. "l" his requiresheavier cyiinder construction than is necessary 'to withstand the pressures developed, and else requires e leo-ser fitting pisten than is necessary with a perfectly round cylinder. The result is that these erigines are not now run es close to best Operating temeraure es possible and are es sarily lac-ewt jacket ie provided on eac i being 'she cyin er G reet the inner jacket. The flow of heated medium is from the head of'the cylinder inward, thence to the outer jacket and preferably helicalr thereof outwardly until the now cooled uid enters the outer end. of the inne-1' jacket. The cooled medium is heavier than the heated medium, and hence the centrifugal force due to the revolution of the cylinder causes the heated medium to flow inwardly in the inner jacket and the increasing density of the fluid in the outer jacket as it cools caums it to flow outiwardly through the outer jacket as it cools and becomes heavier. Although each cylinder may he treeted as a separate unit, the cylinders are herein shownas connected to a common expensible reservoir which compensates for the difference in Volume of the cooling fluid at difi'erent temperatures, and also vents any gases which may be trapped in the fluid.

In the acoompanying drawings- Figure 1 is a diagram illstrating the method, r

Figure 2 is a. View partly in vertical section of e portion oli a Gnome engine emhodying the invention,

Figure 3 is a detail oi" a modification, and

Figire shows the vent valve.

1 represents the stationary hollow crank shai't carrying the crank pin 2, master' ring 3 to which are connected the master connecting rod e and the several jointed con nected rods, 5, 5. 6 is the casing carrying engine cylinders 7, and journaled et its ends to rotate en the crank shaft l. The fuel and lubricating oil are supplied to the interior of the crank casing 6 in the usual nienner, passing through nlet val /'es 9 in istons 10 io the ring space 11 the bnrned gas'es passing out through exhaust va-lve 12. 13 is a hood -for accelerating the exhaust of theburned gases. Any desred valve actuetng mechenisms can heused, es the same are not necessary for an Understanding of this invention and ere not illustrated heroin. 14: is a hele to receive the sparlr plug.

The eylirders 7 ere mode as thin as possihie since they only here to Withstand the ihternei pressures developed without being sul-s eci; disortion hy reason of unequal g.. the istons 10 are similarly d or" l i ht elloy and in the i ieerence then is con Closely surrounding the cylinder so as to form the fluid space lis a generally cylindrical inner jacket 17, which is made of light sheet metal having high heat conducting Capacity, such as aluminum, and it is rolled or scored so as to have screw threads 18 to 'receive the helical outer jacket 19. 20 are one or more ports connectng the lower end of the inner jacket 17 with the lower end of the outer jacket 19, the outer jacket being constructed to be screwed onto the inner jacket. The lower ends of the two jackets are clamped tight by a suitable clampin ring 21. At the upper end, the helical acket 18 cornrnnnicate with the space 22 at the upper end of the inner jacket. As shown heroin, the outer jacket is clamped to the cylinder head by nut 23. There is thus provided a cylindrical fluid space close to the cylinder which is connected at each end to the helical external fluid passage, and in the case of a revolving engine 'the spirals are 'made in' such a way that the centrifugal force assists in making the cool fluid ascend the spiral outwardly to the head of the jacket. As the fluid is heated inside the inner jacket by contact with the thin walled cylinder, it becomes lighter and thus tends to flow inward. The helical outer jacket is made of similar light and thin sheet metal having good conductivity providing a large` amount of air cooling surface. the circulation outside, the fluid passes alternately from a hot to a cold' side of the jacket, all the while moving helicaily toward the head of the cylinder, so that there is no unequal heating of the cylinder wall itself due to one side being cooler than the other on account of the movement of the cylinder itself. Figure 2 shows a single outside helical passage, which will of course be proportioned according to its radiating surface and area to give the proper volume of fluid flow. in Figure 3 multiple helices 24, 25 are shown, forming parallel passages, which are 'of s'onewhat greater pitch than the single helix, hut it will be understood that in all cases the pitch will he roportioned according to the design of tae engine as well as the passage areas. More than two helices Ina be used where desirechas will be well un erstood'. i

lt will be seen that hy this method of cooling, full advantage can he taken of the centrifugal force due the movement ot the cylinders, and in the case ot aviation engines a heavy oil or other iiqnid will preferahly be used as the cooling medium, because hy eliminating distortion ot the eylinder due to unequal cooling the working temperature can be considerahly 26 is a ring shaped reservoir, which may he in the form of aresilient diaphragn so as to expand and contraot in voiume with the eapansion and contra-action of the cooling Owing to fluid. This reservoir is connected to each cylinder, or separately to each' one as 'by pipes 27, 28 thereby keeping the system always full of fluid. Air or other gases in the fluid are vented through a relief valve 29, carryin a protecting cap 30, shown in section in igure 4. The cooling fluid can be either water, or preferably a heavy oil having a higher working temperature than water, because the oil will increase the work- 7 6 ing temperature of the engine and hence in crease the thermal efi'iciency, a heavy oil for aviation having the further advantage that it will not freeze at low ternperatures.

A pump can he used to accelerate the circuse lation if desired, in either a stationary or a rotary cylinder engine. A It will be seen that a rotary cylinder engine by reason of the helical external jacket will he evenly cooled on both sides, while the same will apply to 35 a stationary engine having a fan at one side of the cylinder according to common automobile practice. Also, reater cooling on one side than on the ot er of the helical jacket will accelerate the flow, especially in go a rotary engine. The heices will he wound in such awav that the cooling on one side will, especially n a rotary cylnder engine,

-acelerate the movement through the spirals,'

producing a whirlng movement of the fluid throu h the external jacket. It will he seen that t e action of the helices is to equalize the temperature ofthe internal jacket even though a certain amount of direct radiation i is permitted from the internal jacket, as 10@ shown herein, or directly from the cylinder,

since it is not essential that the interier jacket be uninterrupted circumferentially as long as it is so constrncted that the flow in the interier jacket is longitudinal of the cylinder. It will be understood that the terms heat ahsorbing and heat radiating are used herein in the relative sense, and that the functions ofthe jackets, as well as the flow may in many instances be reversed. lt ne will, therefore, he understood that l do not restrict the invention to the precise constrno tion or use herein shown, as the method can be carried out by various other forms of Construction and in other machines, while the Construction itself is not to he limited except as required by the scopo oi' the appended claims.

What is claimed is:

l. lln conhination with an internal cornme means for causing circnlation of a heat ebiee sorhing fluid through said helical jacket to equalize circurnterentially the temperature of the first said jacket.

2. in comhination with an internal comhustion engine cylinder, a jacket for maintaining a heat absorbing fluid in contact therewith and a second jacket encasing first said jacket and comprising a helical passagecausing the circulation of a heat absorbing fluid through said jackets.

. 4. In combination with an internal combustion engine cylinder, a jacket for maintaining a heat absorbing fluid in contact therewith, and a second jacket encasing first saidjacket and 'comprisng a multiple heli' cal passageway communicating at ts` ends with the respective ends of first said jacket.

5. In combination with a cylinde of an internal combustion engine of the 'rotating cylindertype, a jacket' for maintaining 'a heat absorbing fluid in'contact therewith, and a second jacket-encasing first said jacket and comprs'ing a helical passageway communicating at' its ends. 'with the respective ends of first said jacket. v

6. In combination with a 'cylinder of an` internal combustion engine of the rotating cylinder type, a jacket for 'maintain-ing a heat absorbing fluid in contact therwth, and a second jacket encasing first said :jacket and comprising a helical passa'geway communicating at its ends with the respective ends of firstsaid jacket so that centr'ifugal force will cause the relatively cooler fluid in the second said jacket to move outwardly and to force the relatively warmer .fluid in the first said jacket to move inwardl'y, thus establishing crculation.

7. In combination with an' internal combustion engine cylinder, a cylindrical jacket having a thread thereo`nand an outer heli- -cal jacket threaded thereon.

8. The method of cooling an'internal combustion engine cylinder which' '-c.0nsists in passing a he'at absorbing medium longitudinally of and in contact on all sides with saidcylinder, and of returning said medium in a path external, ad'jacent and helical to its path while incontact with said cylinder, to permit cooling of 'the medium returned, and to equalize circumferentially the temperature of the medium in contact with the cylinder.. e

9. 'The 'method ofcooling an internal combustion engine cylinder which consists in efl'ecting flow of fluid in contact with the cylinder to 'absorb heat therefrom and returning the. 'fluid externally of the cylin'der and of the path of its first said flow, and adjacent the'eto, for cooling said fluid, in such manner that. the flow of relatively cool fluid continuously crosses the flow of rela tivelyhot fluid.

10. The method of cooling a cylinder of 'an internal combustion engine'- of the rotating cylinder type, which consists in efl'ecting a flow of fluid in contact with the cylinder to absorb heat therefrom, and returning the fluid externally of-the 'cylinder and of the path of its first said flow', and adjacent thereto, for cooling said' fluid, in such manner that the flow of relatively cool fluid continuously crosses the flow of relatively hot fluid, said flow being actuated by the centrifugal force set up n the fluid by rotation of the cylinder.

11. A rotary cylinder engine comprising a casing carrying a' plurality of rotary cylinders, a heat absorbing jacket and a connected heat radiating jacket on each cylindemand an expansible fluid reservoir connected to said jackets.

12.' A cooling jacket for' a cylinder comprising an inner cylindrical jacket within an outer helical jacket, the latter being connected at its ends to the ends of the former, and the ends' of said assembled jacket being formed to be Secured on and fastened 'to a cylinder or the like.

Signed at New York city, in the County of New York and State of New York;

j WILLIAM HARPER, J B. 

